4 Days With Rx400h

[ihpj]

Model: X5 xDrive 30d SE

OTR Price: £40,100

Fuel: Diesel

BIK (%): 33%

CO2 (g/km): 214

Combined fuel consumption (mpg): 34.9

Performance (hp): 235

0-62mph (secs): 8.1

cant quiet get your comment on the fact that diesels are not ideal for city /town driving - most taxi's are still diesel

rest my case as it is a step forward into developing alternative mods of transport / wonder what your thoughts would be on Hydrogen-fueled car or perhaps the 400h should have a B.M.W diesel engine fitted and now back to the IS forum

Well I was suggesting that, in door-to-door town-in-town driving only, these types of short runs would not be conducive to a diesel engine giving best economy. Taxis tend to spend most of their time running once started.

The 400h has moved the case for alternative fuel cars forwards, and shown what can be done. And I have acknowledged before that speaking from a BIK tax POV, the RX is unmatched in its class. But I am not a company car driver and have to put my hand into my own pocket to cover all costs when it comes to my car. So BIK holds no relevance to me - emissions are important to me as they determine what RFL I pay. With the way the RFL bands are structured currently, other diesel SUVs cost the same to tax as the 400h and do pretty much the same (if not better) job.

As for diesel engine technology, the Germans are leading the way and Merc are licencing BMWs diesel engine technology for their uses.

[jaroph]

I do not doubt that in town (and town only) the 400h is able to return 30MPG - in fact that would be better than a diesel as this is not an ideal use for a diesel. However point #3 does hold a novelty value no doubt - silent running. But that is precisely what it is, a novelty. Which leads onto point #4 that, as the 400h runs in, it is possible to run it on Battery for those sorts of speeds, but y.....

I beg to differ. I routinely get 32mpg on runs from Calais to Bordeaux - and that is while using the excellent Toll roads where the speed limit is 80MPH

[ihpj]

I beg to differ. I routinely get 32mpg on runs from Calais to Bordeaux - and that is while using the excellent Toll roads where the speed limit is 80MPH

...and I get 30MPG (@70MPH) in my petrol-only RX300. Do wonder what the (fuel efficient) RX350 will return. However @ 80MPH mine will return around 25MPG. But what i was trying to say was that I have no doubt that the 400h excells in 'in town' driving @ 30MPG; a fact I do not dispute and indeed credit to it.

However you are talking about highway/long distance driving - something totally differnet and a figure no doubt achieveable by any decent diesel SUV ;)

[Rillo]

My 2p worth as an RX350 driver who has driven 400 a couple of times. Obviously they both share the same fundamentals other than drive train so I won't comment on those - you either like the RX or you don't.

However a few things I did notice were :

1) Under relatively hard acceleration the front wheels really struggle for grip (a problem my AWD 350 does not). I got the TRC lights on very easily. I found this disconcerting.

2) I found the transmission of power to rear wheels to be quite slow - so there seemed to be a second whilst the fronts spun madly and then the power was shunted backwards. Not a great problem but not smooth

3) In cold weather even after fully warming up the engine was running most of the time - I got 28.1 mpg on same journey I would have seen 22mpg in my 350

4) brakes are very sharp / on-off in nature. may be because of the recharging stuff but found it hard to stop smoothly.

5) very heavy steering compared to my 350

6) feels like a very very heavy car

7) Motorways - where most of my time is spent - not enough increased mpg to justify the added purchase expense.

so overall would I be happy when coming to buy a new RX to have hybrid - sure. However I have to agree that whilst hybrid is a good technology it needs some work and certainly I wouldn't trade in my 350 for one just yet.

[lfoggy]

One weakness of diesel engines, particularly large ones, is that they take quite a while to warm up and until they are up to temperature the fuel consumption is high. A 3 litre Audi A6 for example takes about 5 miles of driving before the temperature gauge stabilises. If you use a diesel for frequent short trips you may be disappointed by the consumption. Petrol engines warm up much more quickly and operate at maximum efficiency almost from the moment you drive away.

[swager]

Model: X5 xDrive 30d SE

OTR Price: £40,100

Fuel: Diesel

BIK (%): 33%

CO2 (g/km): 214

Combined fuel consumption (mpg): 34.9

Performance (hp): 235

0-62mph (secs): 8.1

cant quiet get your comment on the fact that diesels are not ideal for city /town driving - most taxi's are still diesel

rest my case as it is a step forward into developing alternative mods of transport / wonder what your thoughts would be on Hydrogen-fueled car or perhaps the 400h should have a B.M.W diesel engine fitted and now back to the IS forum

Well I was suggesting that, in door-to-door town-in-town driving only, these types of short runs would not be conducive to a diesel engine giving best economy. Taxis tend to spend most of their time running once started.

The 400h has moved the case for alternative fuel cars forwards, and shown what can be done. And I have acknowledged before that speaking from a BIK tax POV, the RX is unmatched in its class. But I am not a company car driver and have to put my hand into my own pocket to cover all costs when it comes to my car. So BIK holds no relevance to me - emissions are important to me as they determine what RFL I pay. With the way the RFL bands are structured currently, other diesel SUVs cost the same to tax as the 400h and do pretty much the same (if not better) job.

As for diesel engine technology, the Germans are leading the way and Merc are licencing BMWs diesel engine technology for their uses.

Hi Ihpj,

last on on the issue of diesel engines,driving our new mini copper diesel and new 320D they both cut out in traffic when you stop and then start when press the clutch in - thus door to door stop start and still get very good m.p.g and both warm up very quickly from cold .

cheers

swager

[ihpj]

last on on the issue of diesel engines,driving our new mini copper diesel and new 320D they both cut out in traffic when you stop and then start when press the clutch in - thus door to door stop start and still get very good m.p.g and both warm up very quickly from cold .

swager

Yes you are right, but the examples you cite are of 'efficiency dynamic' vehicles from BMW that are specifically designed in this way - however taking a non-ED 320d you would find the mileage poor for a diesel in town only driving. You have very kindly illustrated my point that the case for hybrids is weak in comparison to similarly sized hybrids (not only in terms of emissions but handling and drive ability) as the BMW ED vehicles have pushed the bar of the traditional engined vehicles further against the hybrids. But we're not talking about ED diesels - we're talking about 'normal' engined diesels that will be inherently inefficient in town only driving. Try a RR Sport Diesel for example ;)

I have come over to Lexus from BMW - I know my BMW products too mate ;)

[swager]

last on on the issue of diesel engines,driving our new mini copper diesel and new 320D they both cut out in traffic when you stop and then start when press the clutch in - thus door to door stop start and still get very good m.p.g and both warm up very quickly from cold .

swager

Yes you are right, but the examples you cite are of 'efficiency dynamic' vehicles from BMW that are specifically designed in this way - however taking a non-ED 320d you would find the mileage poor for a diesel in town only driving. You have very kindly illustrated my point that the case for hybrids is weak in comparison to similarly sized hybrids (not only in terms of emissions but handling and drive ability) as the BMW ED vehicles have pushed the bar of the traditional engined vehicles further against the hybrids. But we're not talking about ED diesels - we're talking about 'normal' engined diesels that will be inherently inefficient in town only driving. Try a RR Sport Diesel for example ;)

I have come over to Lexus from BMW - I know my BMW products too mate ;)

Ihpj,

What I am talking about is modern engines and design coupled with innovation and also the way I think manufacturers will have to go to survive .The RX400h is a great vehicle and if you can adjust your style of driving will give impressive fuel consumption in urban driving conditions and IMO if Lexus would have developed a class leading diesel engine (not based on the IS220d)and fitted it into the RX400h wow it would be a class leader .Just as a matter of interest Ihpj have you ever driven a RX400h for any length of time ????

merry crimbo

swager

[ihpj]

Just as a matter of interest Ihpj have you ever driven a RX400h for any length of time ????

merry crimbo

swager

Merry XMAS to one and ALL! :D

And yes, I have had the use of one for about 6 - 8 weeks in Sept. 2007 - and I posted my experience in great detail on this forum (I am sure you will find the thread if you search).

But as for the diesel engine theme, the Japanese are going down the road of hybrid, while the Germans are going down the diesel route. It is, as I have remarked elsewhere, a marketing ploy whereby it helps differentiate products in the market. I doubt Lexus will ever produce a diesel engine that can compete with BMW/Merc/VAG - because for them it is all about the technology: hybrid. And IIRC Lexus will be looking to sell hybrid only vehicles from 2010/11?

Good luck to Lexus and the Japanese for their advancements. Comepetitive market can only benefit everyone. When (note not IF) hybrid gets improved and perfected, none will be more happier to buy in than me. But until then, I will take a modern diesel over a hybrid SUV these days.

[GBR134]

Model: X5 xDrive 30d SE

OTR Price: £40,100

Fuel: Diesel

BIK (%): 33%

CO2 (g/km): 214

Combined fuel consumption (mpg): 34.9

Performance (hp): 235

0-62mph (secs): 8.1

cant quiet get your comment on the fact that diesels are not ideal for city /town driving - most taxi's are still diesel

rest my case as it is a step forward into developing alternative mods of transport / wonder what your thoughts would be on Hydrogen-fueled car or perhaps the 400h should have a B.M.W diesel engine fitted and now back to the IS forum

Well I was suggesting that, in door-to-door town-in-town driving only, these types of short runs would not be conducive to a diesel engine giving best economy. Taxis tend to spend most of their time running once started.

The 400h has moved the case for alternative fuel cars forwards, and shown what can be done. And I have acknowledged before that speaking from a BIK tax POV, the RX is unmatched in its class. But I am not a company car driver and have to put my hand into my own pocket to cover all costs when it comes to my car. So BIK holds no relevance to me - emissions are important to me as they determine what RFL I pay. With the way the RFL bands are structured currently, other diesel SUVs cost the same to tax as the 400h and do pretty much the same (if not better) job.

As for diesel engine technology, the Germans are leading the way and Merc are licencing BMWs diesel engine technology for their uses.

Hi Ihpj,

last on on the issue of diesel engines,driving our new mini copper diesel and new 320D they both cut out in traffic when you stop and then start when press the clutch in - thus door to door stop start and still get very good m.p.g and both warm up very quickly from cold .

cheers

swager

Yep and my first car was a 1967 850 cc Austin Mini could get 45+ mpg on a good day but was not comparable in any other way! Lexus themselves promote the hybrid as a Luxury Car that reduces pollution where it is at its worst - City Centres. However Luxury and Performance come first. My Neighbour drives a 350 I have a 400H and we often debate their merits. My thoughts are this:-

You want really good economy - look elsewhere

you want really good handling - don't buy any SUV

You only need to accelerate hard when being annoyed by a kid in a Corsa - RX is great

You want to waft round in Luxurious comfort RX is the car

Only race a Cayenne off the lights not on the open road

400h or 350 i use @ 1/4 less petrol than the neighbour which will take an awful long time to break even on @£10 k price difference.

Mine is a company car - 400H is obvious (BIK) his is private 350 wins.

My next car - Probably Audi, Neighbours next car defo RX probably 400H ( he loves the Tesco car park effect in mine!)

[lfoggy]

There is no point in comparing diesel and petrol powered cars by comparing the fuel consumption in miles per gallon. Petrol contains nearly 20% less energy per unit volume than diesel. It is a less dense fuel and contains less carbon and less chemical energy per unit volume. Similarly a litre volume of coal contains far more energy and a litre volume of methane far less energy than a litre of petrol.

A somewhat more meaningful comparison is the carbon emissions in g/km but expressing efficiency in terms of distance travelled per joule of thermal energy is the most logical (although rarely done).

It is a failure to recognise this fact that has given diesel powered vehicles an enhanced reputation for efficiency compared to petrol vehicles over the years. The true thermal efficency of diesel engines is ony a few percent better than petrol engines at best.

The cost or running a diesel vs petrol car has more to do with the local pricing of the fuels than anything else. In the UK the tax reflects the carbon content of the fuel but on the continent this is generally not the case. This has LED to a huge drive by European manufacturers to develop diesel engines. In America and Japan there has been no such pressure and petrol is still the dominant fuel.

Finally, diesel engines are favoured by truck and taxi manufacturers more for their reliability and longevity than thermal efficiency.

Personally I prefer the driving characteristics of petrol engines and Toyota make very refined engines indeed.....

[NickS]

Thanks, Ifoggy, for the most interesting contribution to a good debate. Most of us probably look more simplistically at the cost per mile, and the tax implications, whether a company vehicle or private. Buying a Lexus in my case was more a matter of heart over head, as I find it pretty hard to justify, when a Skoda Octavia would probably deliver the same space and reliability (and a good measure of comfort) with much lower ownership costs. Of course, I never expected the depreciation to reach £1000 per month - at the current rate I'll be paying the dealer to take it away within a year!

NickS